export type TokenType =
	| "tag"
	| "text"
	| "code"
	| "out"
	| "comment"
	| "doctype"
	| "keyword"
	| "frontmatter"
	| "test"
	| "rawtext";

export interface RawAttribute {
	name: string;
	value?: string;
	kind: "string" | "expression" | "boolean";
}

/** A single line of a template, already split into its semantic parts. */
export interface Token {
	type: TokenType;
	/** Indentation width, used to build the tree. */
	indent: number;
	/** Line number in the source file, used for error messages. */
	line: number;
	/** Raw text of the line. */
	value: string;
	/** Tag name, only for `tag` tokens. */
	name?: string;
	/** Attributes, only for `tag` tokens. */
	attributes?: RawAttribute[];
	/** Inline text following the tag, only for `tag` tokens. */
	text?: string;
	/** Buffered expression of the tag, e.g. `p= title`. */
	output?: string;
	/** Keyword name, only for `keyword` tokens. */
	keyword?: string;
	/** Keyword payload (`each item in items`), only for `keyword` tokens. */
	keywordValue?: string;
	/** Whether the tag is followed by a block of raw text (`p.`). */
	blockText?: boolean;
	/** A generated relation identity declared with `tag@name()` in SPUG. */
	anchor?: { name: string; expression?: string };
	/** Whether a comment is silent (`//-`). */
	silent?: boolean;
	/** Whether an output expression is escaped (`=` vs `!=`). */
	escaped?: boolean;
}

export type TextPart =
	| { type: "literal"; value: string }
	| { type: "expression"; code: string; escaped: boolean };

export interface PropDeclaration {
	name: string;
	/** Type expression as written in the template. */
	type: string;
	optional: boolean;
	/** Default value expression, when declared with `=`. */
	defaultValue?: string;
}

export interface ElementNode {
	kind: "element";
	name: string;
	attributes: RawAttribute[];
	children: Node[];
	selfClosing: boolean;
	/** A generated relation identity declared with `tag@name()` in SPUG. */
	anchor?: { name: string; expression?: string };
}

export interface TextNode {
	kind: "text";
	parts: TextPart[];
}

export interface RawTextNode {
	kind: "rawtext";
	value: string;
}

export interface CodeNode {
	kind: "code";
	code: string;
}

export interface OutNode {
	kind: "out";
	code: string;
	escaped: boolean;
}

export interface CommentNode {
	kind: "comment";
	value: string;
	silent: boolean;
	children: Node[];
}

export interface DoctypeNode {
	kind: "doctype";
	value: string;
}

export interface IfBranch {
	/** `null` marks the `else` branch. */
	test: string | null;
	negate: boolean;
	children: Node[];
}

export interface IfNode {
	kind: "if";
	branches: IfBranch[];
}

export interface EachNode {
	kind: "each";
	value: string;
	key?: string;
	list: string;
	children: Node[];
}

export interface WhileNode {
	kind: "while";
	test: string;
	children: Node[];
}

export interface CaseNode {
	kind: "case";
	subject: string;
	cases: { test?: string; children: Node[] }[];
}

export interface MixinDefNode {
	kind: "mixin";
	name: string;
	params: string;
	children: Node[];
}

export interface MixinCallNode {
	kind: "mixin-call";
	name: string;
	args: string;
	children: Node[];
}

export interface IncludeNode {
	kind: "include";
	path: string;
	/** Included file content, resolved by the linker. */
	children: Node[];
}

export interface ExtendsNode {
	kind: "extends";
	path: string;
}

export interface BlockNode {
	kind: "block";
	name: string;
	mode: "replace" | "append" | "prepend";
	children: Node[];
}

export interface SlotNode {
	kind: "slot";
	name: string;
	children: Node[];
}

export interface YieldNode {
	kind: "yield";
	name: string;
}

export interface PropsNode {
	kind: "props";
	props: PropDeclaration[];
}

export interface ComponentNode {
	kind: "component" | "island";
	name: string;
	/** Prop name to expression. */
	props: Record<string, string>;
	/** Renderers that are applied inline by the component. */
	renders: { name: string; children: Node[] }[];
}

/**
 * A block of assertions.
 */
export interface TestNode {
	kind: "test";
	/** The assertions of the block. */
	code: string;
}

/**
 * A renderer that is applied inline.
 */
export interface RenderNode {
	kind: "render";
	/** Name of the prop the renderer is handed to. */
	name: string;
	children: Node[];
}

export interface PortalNode {
	kind: "portal";
	name: string;
	children: Node[];
}

export type Node =
	| ElementNode
	| TextNode
	| RawTextNode
	| CodeNode
	| OutNode
	| CommentNode
	| DoctypeNode
	| IfNode
	| EachNode
	| WhileNode
	| CaseNode
	| MixinDefNode
	| MixinCallNode
	| IncludeNode
	| ExtendsNode
	| BlockNode
	| SlotNode
	| YieldNode
	| PropsNode
	| ComponentNode
	| TestNode
	| RenderNode
	| PortalNode;